Subject: Re: [linux-audio-dev] Re: EVO-Linux Physical Modeling HD Sampler
From: David Olofson (david_AT_gardena.net)
Date: Tue Jul 18 2000 - 05:31:41 EEST
Need some sleep, but I'll try to comment briefly on this first.
On Mon, 17 Jul 2000, Benno Senoner wrote:
> Ok let's start:
>
> VOICE:
>
> a voice is basically a sample played back by the engine which has the
> following characteristics:
>
> - pointer to sampled data
> - len of sampled data
> - loop point begin , loop point end
> - oneshot / looped
Although you can do most things you want with this, multiloops (ie a
list of regions, rather than a single loop) may be worth
investigating...
> - base volume
> - base pitch
> - base panorama (balance)
> - base filter cutoff
> - base filter resonance
Filter types?
> for each parameter
> (volume , pitch , pan , cutoff and resonance)
>
> there is an:
> attack envelope
> sustain envelope
> release envelope
>
> each envelope is an arbitrary succession straight lines
> which consist of:
>
> validity in number of samples
> starting value
> delta per sample ( can be positive and negative,
> higher values will produce steeper , lower values flatter lines)
With quadratic splines:
validity in number of samples
starting value
delta per sample
delta change per sample
There's another problem here, though; envelope timing may need to be
scaled along with pitch and other things.
[...]
> Another thing we could do is to map a MIDI controller
> to different envelope structures, so that
> differen controller values (the modwheel or breath-controller)
> could for example change the attack behaviour of the sample
> at the next note trigger.
> (would this feature be useful ?)
This could be a way to solve the issue mentioned above. No big
problem with data size, and editors can generate the timestretched
envelopes when saving the files. How to load them back into something
editable, though...?
> Obviously the voices will be routable through a FX section
> (the FXes should be loadable plugins) , with dry/wet parameter.
Better do this real. There are at least 4 standard MIDI CCs for
effect send levels, two of which are supported by most synths and
samplers with built-in FX. Two is pretty restrictive for a full
arangement, considering that a really good sampler should be able to
handle *all* sounds in many kinds of arrangements, so at the very
least, the 4 standard sends should be implemented. Preferably
something more powerful and more generic.
Finally, don't regard MIDI as the True Model to design the sampler
around! MIDI has too low controller resolution, no timestamps, only
16 channels/port, only pitch + velocity data inside NoteOn events etc
etc... Not that I'm expecting MIDI to be replaced any time soon, but
at least, accepting the *figures* defined by MIDI as the measures for
how many Fx sends there should be and that kind of stuff might result
in somewhat illogical restrictions. Adopt the MIDI implementation
(CC, BC and PC mapping for example) to the sampler rather than the
other way around, within sensible limits. Just something to consider
before hardcoding MIDI into the engine core forever, perhaps.
//David
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